The present invention relates to heavy duty shears of the type mountable on mobile construction equipment such as excavating machines and, more particularly, to an improved connection of the shear to the construction equipment.
Heavy duty shears of the type to which the present invention is directed are well known and widely used in demolition, scrap handling, and other areas where large metallic pieces must be reduced in size. Bridge demolition sites, building demolition sites and scrap yards often contain assemblies of I-beams, iron channels, metallic pipes, and other structural components which must be reduced in size and moved. Demolition shears are useful in reducing the size of scrap. It is often necessary to move the shears within a site. Therefore, the shears are often mounted on heavy equipment such as an excavator. This allows the operator to manipulate the shear from the cab of the excavator to pick-up pieces of scrap, reduce them in size and pile them. It also allows the operator to move the shear and the mobile equipment within the site.
Many modem excavating machines are hydraulically operated, supported on tracks on an under carrier and have a rotatable cab mounted on the under carriage. The operational portion of the excavator consists of a rigid boom connected at one end to the rotating portion of the excavator. Hydraulic cylinders control the boom and allow the operator to pivot the boom in a vertical plane. A rigid stick is fixed to the end of the boom away from the cab. The stick also can pivot about the end of the boom in a vertical plane. It is controlled by one or more hydraulic cylinders under the control of the operator. When used as an excavator, a bucket is mounted at the end of the stick with the opening and teeth of the bucket facing the operator. The bucket is also rotatable in a vertical plane by means of one or more hydraulic cylinders under the control of the operator. This arrangement of a boom, a stick and a utensil such as an excavating bucket has proven advantageous and is used in many excavators. It allows the operator flexibility, a long reach and good visibility of the utensil as it works.
The capacity of an excavator to lift or carry a load is determined by a number of factors. One factor is the distance of the load from the center of gravity of the excavator. Thus, an excavator can lift or carry a larger load held close to its center of gravity when compared to lifting the load at a greater distance from the center of gravity. For example, an excavator may be able to lift a particular I-beam located 10 feet from its track without a problem. However, if the same I-beam is 30 feet from the track the excavator may start to tip if it attempts to lift that I-beam with an extended boom and stick.
Demolition shears are typically constructed from steel, are very heavy and very robust. Therefore, the mounting arrangement for these shears are also heavy and robust. They are usually structured with a particular mounting orientation in mind and have the strength to support the structure in that orientation.
While the above-described shear and mounting arrangement provide a great deal of flexibility to operators, more flexibility is always desirable. The more different ways a utensil can be used, the more utility it will have to the end user.